offspring of parents that differ in genetically determined traits. The parents may be of different species, genera, or (rarely) families. The term hybrid, therefore, has a wider application than the terms mongrel or crossbreed, which usually refer to animals or plants resulting from a cross between two races, breeds, strains, or varieties of the same species. There are many species hybrids in nature (in ducks, oaks, blackberries, etc.), and, although naturally occurring hybrids between two genera have been noted, most of these latter result from human intervention.